Nomex??

[mabsmeier]

For under 175mph the rule states "Suit SFI 3.2A/10 or /5 with full Nomex underwear". I'm assuming any SFI rated underwear would do or does it to be made of actual Nomex? ?

[Stainless1]

Nomex is a trademark name, I would guess that any SFI 3.3 rated fire resistant underwear would pass... Back in the day, Nomex was the only one... now there are several...
But WTF do I know... the only answer that counts comes from the SCTA/BNI inspection folks... send 'em an email or give 'em a call.